This invention relates to an electrophotographic plate utilizing a specific metal naphthalocyanine derivative, and also relates to a derivative described above and a process for producing the same.
In recent years, with the advent of laser diodes, films containing compounds having sensitivity to longer wavelength which is the wavelength of laser diodes have been actively developed for utilization for photoconducive layers of electrophotographic plate, photosensitive layers of recording media, display layers of electrochromic display members, electrode layers of photocatalytic electrode reactions, photosensitive layers of chemical sensors, luminescent layers of electro-luminescence, etc.
For example, to describe about electrophotographic plates, as the electrophotographic plates of the prior art, there is one in which selenium (Se) film with a thickness of about 50 .mu.m is formed by the vacuum vapor deposition method on an electoconductive substrate such as aluminum, etc.
However, such Se electrophotographic plate has the problem that it has only sensitivity to wavelengths up to around 500 nm, etc. Also, there is an electrophotographic plate having Se layer with a thickness of about 50 .mu.m on an electroconductive substrate, and further an alloy layer of selenium-tellurium (Se-Te) with a thickness of several .mu.m formed thereon. However, while on one hand such electrophotographic plate can be extended in spectral sensitivity to longer wavelengths as the content of Te in the above Se-Te alloy is increased, on the other hand, surface charges retention properties deteriorate with an increase in the amount of Te added, whereby there is the serious problem that it is no longer useful as the electrophotographic plate.
Also, there is the so called complex double layer type electrophotographic plates produced by forming a charge generation layer on an aluminum substrate by coating chlorocyan blue or squarilium acid derivative with a thickness of about 1 .mu.m and forming a charge transport layer thereon by coating a polyvinylcarbazole having high insulation resistance or high insulation resistance mixture of pyrazoline derivative and a polycarbonate in 10 to 20 .mu.m thickness, but such electrophotographic plates have practically no sensitivity to a light having a wavelength of 700 nm or more.
Further, in the complex double layer type electrophotographic plate, there is also an electrophotographic plate improved in the above drawback, namely having sensitivity to around 800 nm which is laser diode oscillation region. However in many of these electrophotographic plates, a charge generation layer comprising a thin film with a thickness of about 1 .mu.m of a metal phthalocyanine having a metal of the group III or the group IV of the periodic table as the center metal is formed by the vacuum vapor deposition method and thereafter is dipped in a shifting agent solution or contacted with the vapor thereof, thereby to shift the absorption band which is inherently around 700 nm to around 800 nm and to impart longer wavelength sensitivities to the electrophotographic plate.
A complex double layer type electrophotographic plate is formed by forming a charge transport layer on the above charge generation layer by coating with a polyvinylcarbazole having high insulation resistance or a high insulation resistance mixture of a hydrazone derivative or pyrazoline derivative and a polycarbonate or a polyester in 10 to 20 .mu.m thickness. However, in this case, the metal phthalocyanine thin film having a metal of the group III or the group IV of the periodic table as the center metal used as the charge generation layer has essentially no absorption at around 800 nm of the laser diode oscillation region, and there is involved the serious problem that the electrophotographic plate formed by use of this thin film has little or no sensitivity to the light of around 800 nm unless it is treated with a shifting agent (see Japanse Unexamined patent Publication No. 158649/1983).
In laser beam printers by use of an electrophotographic plate having a photoconductive layer, various attempts have been made in recent years to employ a laser diode as the light source, and also developments of films excellent in sensitivity to laser beam have been variously made in other uses. In this case, since the wavelength of said light source is around 800 nm, it is strongly demanded to produce a film which can absorb longer wavelength light of around 800 nm to be converted efficiently to another energy. Also, in the electrochromic display, a film (display layer) capable of being changed in color by efficient electrical redox has been demanded.
Whereas, an information recording medium and an optical information recording medium using a naphthalocyanine derivative are proposed in Japanese Unexamined Patent Publications Nos. 177287/1986 and 177288/1986, but in these publications, there is no description about use of said naphthalocyanine derivative for an electrophotographic plate characterized by achieving recording through charging, exposure and developing.